package se.hjartstartarregistret.m;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Locale;

/**
 * A stripped down copy of the apache commons-lang StringEscapeUtils:
 * 
 * <p>
 * Escapes and unescapes <code>String</code>s for Java, Java Script, HTML, XML,
 * and SQL.
 * </p>
 * 
 * @author Apache Jakarta Turbine
 * @author Purple Technology
 * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
 * @author Antony Riley
 * @author Helge Tesgaard
 * @author <a href="sean@boohai.com">Sean Brown</a>
 * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
 * @author Phil Steitz
 * @author Pete Gieser
 * @since 2.0
 * @version $Id: StringEscapeUtils.java 2696 2007-06-20 13:24:53Z damencho $
 */
public class StringEscapeUtils {

	private StringEscapeUtils() {
	}

	/**
	 * <p>
	 * Escapes the characters in a <code>String</code> using JavaScript String
	 * rules.
	 * </p>
	 * <p>
	 * Escapes any values it finds into their JavaScript String form. Deals
	 * correctly with quotes and control-chars (tab, backslash, cr, ff, etc.)
	 * </p>
	 * 
	 * <p>
	 * So a tab becomes the characters <code>'\\'</code> and <code>'t'</code>.
	 * </p>
	 * 
	 * <p>
	 * The only difference between Java strings and JavaScript strings is that
	 * in JavaScript, a single quote must be escaped.
	 * </p>
	 * 
	 * <p>
	 * Example:
	 * 
	 * <pre>
	 * input string: He didn't say, "Stop!"
	 * output string: He didn\'t say, \"Stop!\"
	 * </pre>
	 * 
	 * </p>
	 * 
	 * @param str
	 *            String to escape values in, may be null
	 * @return String with escaped values, <code>null</code> if null string
	 *         input
	 */
	public static String escapeJavaScript(String str) {
		return escapeJavaStyleString(str, true);
	}

	/**
	 * <p>
	 * Worker method for the {@link #escapeJavaScript(String)} method.
	 * </p>
	 * 
	 * @param str
	 *            String to escape values in, may be null
	 * @param escapeSingleQuotes
	 *            escapes single quotes if <code>true</code>
	 * @return the escaped string
	 */
	private static String escapeJavaStyleString(String str,
			boolean escapeSingleQuotes) {
		if (str == null) {
			return null;
		}
		try {
			StringWriter writer = new StringWriter(str.length() * 2);
			escapeJavaStyleString(writer, str, escapeSingleQuotes);
			return writer.toString();
		} catch (IOException ioe) {
			// this should never ever happen while writing to a StringWriter
			ioe.printStackTrace();
			return null;
		}
	}

	/**
	 * <p>
	 * Worker method for the {@link #escapeJavaScript(String)} method.
	 * </p>
	 * 
	 * @param out
	 *            write to receieve the escaped string
	 * @param str
	 *            String to escape values in, may be null
	 * @param escapeSingleQuote
	 *            escapes single quotes if <code>true</code>
	 * @throws IOException
	 *             if an IOException occurs
	 */
	private static void escapeJavaStyleString(Writer out, String str,
			boolean escapeSingleQuote) throws IOException {
		if (out == null) {
			throw new IllegalArgumentException("The Writer must not be null");
		}
		if (str == null) {
			return;
		}
		int sz;
		sz = str.length();
		for (int i = 0; i < sz; i++) {
			char ch = str.charAt(i);

			// handle unicode
			if (ch > 0xfff) {
				out.write("\\u" + hex(ch));
			} else if (ch > 0xff) {
				out.write("\\u0" + hex(ch));
			} else if (ch > 0x7f) {
				out.write("\\u00" + hex(ch));
			} else if (ch < 32) {
				switch (ch) {
				case '\b':
					out.write('\\');
					out.write('b');
					break;
				case '\n':
					out.write('\\');
					out.write('n');
					break;
				case '\t':
					out.write('\\');
					out.write('t');
					break;
				case '\f':
					out.write('\\');
					out.write('f');
					break;
				case '\r':
					out.write('\\');
					out.write('r');
					break;
				default:
					if (ch > 0xf) {
						out.write("\\u00" + hex(ch));
					} else {
						out.write("\\u000" + hex(ch));
					}
					break;
				}
			} else {
				switch (ch) {
				case '\'':
					if (escapeSingleQuote) {
						out.write('\\');
					}
					out.write('\'');
					break;
				case '"':
					out.write('\\');
					out.write('"');
					break;
				case '\\':
					out.write('\\');
					out.write('\\');
					break;
				default:
					out.write(ch);
					break;
				}
			}
		}
	}

	/**
	 * <p>
	 * Returns an upper case hexadecimal <code>String</code> for the given
	 * character.
	 * </p>
	 * 
	 * @param ch
	 *            The character to convert.
	 * @return An upper case hexadecimal <code>String</code>
	 */
	private static String hex(char ch) {
		return Integer.toHexString(ch).toUpperCase(Locale.ENGLISH);
	}

}